bpf tools: Improve libbpf error reporting
In this patch, a series of libbpf specific error numbers and
libbpf_strerror() are introduced to help reporting errors.
Functions are updated to pass correct the error number through the
CHECK_ERR() macro.
All users of bpf_object__open{_buffer}() and bpf_program__title() in
perf are modified accordingly. In addition, due to the error codes
changing, bpf__strerror_load() is also modified to use them.
bpf__strerror_head() is also changed accordingly so it can parse libbpf
errors. bpf_loader_strerror() is introduced for that purpose, and will
be improved by the following patch.
load_program() is improved not to dump log buffer if it is empty. log
buffer is also used to deduce whether the error was caused by an invalid
program or other problem.
v1 -> v2:
- Using macro for error code.
- Fetch error message based on array index, eliminate for-loop.
- Use log buffer to detect the reason of failure. 3 new error code
are introduced to replace LIBBPF_ERRNO__LOAD.
In v1:
# perf record -e ./test_ill_program.o ls
event syntax error: './test_ill_program.o'
\___ Failed to load program: Validate your program and check 'license'/'version' sections in your object
SKIP
# perf record -e ./test_kversion_nomatch_program.o ls
event syntax error: './test_kversion_nomatch_program.o'
\___ Failed to load program: Validate your program and check 'license'/'version' sections in your object
SKIP
# perf record -e ./test_big_program.o ls
event syntax error: './test_big_program.o'
\___ Failed to load program: Validate your program and check 'license'/'version' sections in your object
SKIP
In v2:
# perf record -e ./test_ill_program.o ls
event syntax error: './test_ill_program.o'
\___ Kernel verifier blocks program loading
SKIP
# perf record -e ./test_kversion_nomatch_program.o
event syntax error: './test_kversion_nomatch_program.o'
\___ Incorrect kernel version
SKIP
(Will be further improved by following patches)
# perf record -e ./test_big_program.o
event syntax error: './test_big_program.o'
\___ Program too big
SKIP
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1446817783-86722-2-git-send-email-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c
index 0c5d174..c46256b 100644
--- a/tools/perf/util/bpf-loader.c
+++ b/tools/perf/util/bpf-loader.c
@@ -59,9 +59,9 @@
} else
obj = bpf_object__open(filename);
- if (!obj) {
+ if (IS_ERR(obj)) {
pr_debug("bpf: failed to load %s\n", filename);
- return ERR_PTR(-EINVAL);
+ return obj;
}
return obj;
@@ -96,9 +96,9 @@
int err;
config_str = bpf_program__title(prog, false);
- if (!config_str) {
+ if (IS_ERR(config_str)) {
pr_debug("bpf: unable to get title for program\n");
- return -EINVAL;
+ return PTR_ERR(config_str);
}
priv = calloc(sizeof(*priv), 1);
@@ -308,13 +308,34 @@
return 0;
}
+static int
+bpf_loader_strerror(int err, char *buf, size_t size)
+{
+ char sbuf[STRERR_BUFSIZE];
+ const char *msg;
+
+ if (!buf || !size)
+ return -1;
+
+ err = err > 0 ? err : -err;
+
+ if (err >= __LIBBPF_ERRNO__START)
+ return libbpf_strerror(err, buf, size);
+
+ msg = strerror_r(err, sbuf, sizeof(sbuf));
+ snprintf(buf, size, "%s", msg);
+ buf[size - 1] = '\0';
+ return 0;
+}
+
#define bpf__strerror_head(err, buf, size) \
char sbuf[STRERR_BUFSIZE], *emsg;\
if (!size)\
return 0;\
if (err < 0)\
err = -err;\
- emsg = strerror_r(err, sbuf, sizeof(sbuf));\
+ bpf_loader_strerror(err, sbuf, sizeof(sbuf));\
+ emsg = sbuf;\
switch (err) {\
default:\
scnprintf(buf, size, "%s", emsg);\
@@ -345,8 +366,6 @@
int err, char *buf, size_t size)
{
bpf__strerror_head(err, buf, size);
- bpf__strerror_entry(EINVAL, "%s: Are you root and runing a CONFIG_BPF_SYSCALL kernel?",
- emsg)
bpf__strerror_end(buf, size);
return 0;
}